GENE EXPRESSION PROFILES OF GROWTH AND REPRODUCTION RELATED GENES DURING THE EARLY DEVELOPMENT OF COMMON CARP(CYPRINUS CARPIO L. )

As many researches revealed some relations between HPG and GH/IGF axis in teleost,we detected gene expression profiles of growth-and reproduction-related genes from HPG or GH/IGF axis in common carp(Cyprinus carpio) embryos and early larval stages,in order to find some regulatory relations between HPG and GH/IGF axis in the early development stages of common carp.The genes under detection were sGnRH,cGnRH,GtH α subunit and β subunit from HPG axis and GH,IGF,growth hormone receptor(GHR) from GH/IGF axis,with β-actin gene as the internal control.Samples were collected from embryos and larvae of unfertilized eggs,64-cell stage,32-cell stage,256-cell stage,50%-epiboly,20-,23-,26-,32-,40-,46-and 58-hours post fertilization(hpf),and 1-,2-,3-,5-,7-and 9-days post hatching(dph) reared at 23℃,and then RNA extracted from the samples was used in RT-PCR.sGnRH,cGnRH,GtH α subunit,GtH-I β subunit,GtH-II β subunit,GH,GHR and IGF-1 showed different expression patterns in carp embryos and larvae.Development around 20h post fertilization(hpf) and 23hpf was critical for carp embryos,as sGnRH,cGnRH,GtH-I β subunit and GHR were first detectable at 20hpf,IGF-1 at 23hpf and GtH-II β at 26hpf.Meanwhile,embryos in 20hpf and 23hpf stages showed apparent development in brain region,indicating a regulatory function of GnRH and GtH in the development of brain.GtH α subunit was first detectable at 46hpf while GH was first detectable at 1d post hatching(dph).The difference in the timing of the expression of GH and IGF mRNA may suggest that IGF gene expression is not GH-dependent.Additionally,the timing of the expression of GtH α subunit,GtH-I β subunit,GtH-II β subunit were unsynchronized in embryos,suggesting a regulatory function of GtH α subunit in GtH expression.